Total synthesis of (.+-.)-.DELTA.9-tetrahydrocannabinol and four of its isomers

Preparation of 2,2-dimethylchroman-4-ones from 5-alkyl-substituted resorcinols: microwave-assisted synthesis and theoretical calculations

“…Examples of these compounds include cannabichromanones identified as components of the Cannabis sativa plant. 2,3 Moreover, 2,2-dimethyl-5-hydroxychroman-4-ones have been described as intermediates in the synthesis of tetrahydrocannabinols 4 and, as we have reported, in the synthesis of cannabinoid chromenopyrazoles. 5 A survey of the preparations of differently substituted 2,2-dimethylchroman-4-ones was published by Tímár et al 6 twelve years ago.…”

Structure-Activity Studies on Tetrahydro- and Hexahydrocannabinol Derivatives

“…It was prepared either as a racemic mixture according to the procedure of Fahrenholtz et a[ (5) or as an optically active compound with the natural configuration according to a slightly improved procedure (6). (-)-A9.l1-Tetrahydrocannabino1 acetate' was treated with osmium tetroxide and sodium periodate in tetrahydrofurar-water to give the ketone after saponification of the acetate in an overall yield of 75%.…”

Esterification of Carboxylic Acids and Etherification of Phenols with Amide Acetals

“…[39][40][41] The analogous reaction of fumaric acid (92) (pK a = 3.03, 4.47) with DMF dimethyl acetal 7a in boiling THF affords, via its corresponding insoluble iminium salt 93 comprising a fumarate dianion and two iminium cations 6a, dimethyl fumarate (94) in near quantitative yield (Scheme 22). 115 Yet the reaction of maleic acid (95) (pK a = 2.00, 6.26), which is a much stronger acid than fumaric acid (92) and, therefore, behaves quite differently, in boiling THF with 1 equivalent of 7a afforded no precipitate of the corresponding iminium salt 96, but only the monomethyl ester 97 after workup which is probably in equilibrium with 98 and 99. The monoester 97-99 can also, however, be readily prepared by keeping a solution of maleic anhydride in excess methanol for about 3 days at ambient temperature and then evaporating the solvent from the reaction mixture in vacuo.…”